So you've tried forwarding ports in your router, turning off your firewall, and you just can't get rid of that yellow light? Here are the usual reasons for unexplained firewalling:

(1) Security software. Norton, McAfee, and other antivirus and network security packages often prevent software from opening server ports. You may need to register your client with the software. You may have more than one piece of software that's blocking server ports. Windows Firewall will block server ports also.

(2) Double-NAT. You may have forwarded ports in your router, but it's surprisingly common that your Cable/DSL modem has a built-in router. To find out, check what your router says is the external IP. (If you're not using a router, check your machine's IP.) If it's in the range 10.x.x.x or 192.168.x.x, your modem is also a router. Try entering in that IP, replacing the last numbers after the dot with a 1 (or after the middle dot with 1.1) into your web browser.